Handover of an MS is a process of migrating the MS from an air interface provided by a Base Station (BS) to an air interface provided by another BS. When signal attenuation or interference occurs, the MS needs to reselect a BS to obtain better signal quality or Quality of Service (QoS) through handover. Currently, commercial MSs generally support handover between BSs that have the same bandwidth only. In the process of implementing the present invention, the inventor finds that, if the MS expects to be handed over to a BS whose bandwidth is different from the bandwidth of the current serving BS, and use the air interface service provided by the BS that has a different bandwidth, the MS has to be restarted to adjust the bandwidth and access the network again, which makes service interruption inevitable. As a result of spectrum division and allocation, one operator usually deploys networks by using BSs with different bandwidths; or, in the case of roaming, the MS runs across BSs with different bandwidths. In such cases, the MS needs to be handed over between BSs with different bandwidths, which generally causes service interruption.